1. Field of the Invention
The present invention relates to a camera lens operating unit, more particularly to a camera lens operating unit that corrects changes of a view angle caused by moving a focus lens of a TV camera.
2. Description of Related Art
In a conventional TV camera, a phenomenon has been observed: when a focussing is performed by moving a focus lens at a state where a zoom lens is set to a widephoto side, a view angle changes as if zooming was performed. This phenomenon is called a pumping phenomenon.
Japanese Patent Application Laid-open No. 6-250071 discloses a lens unit that corrects the pumping phenomenon by automatically adjusting the position of the zoom lens when a focus lens is moved. This lens unit, however, requires a change in process of a control part of the lens unit, so that there is a disadvantage in that this means cannot be applied to a lens unit already in use. In addition, in order to perform the pumping correction, contents of process of the lens unit must be complex; thus an amount of process of the lens unit was increased.
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of a camera lens operating unit which can correct pumping without adding a change to the lens unit.
In order to achieve the above-described objects, the present invention is directed to a lens operating unit for transmitting a driving signal to a lens system having a focus lens, a zoom lens and a lens driver for moving the focus lens and the zoom lens in accordance with the driving signal, the lens operating unit comprising: a focus operating member; a zoom operating member; a lens position receiver for receiving a position signal representing positions of the focus lens and the zoom lens from the lens system; a storage device for storing data used to obtain a target position of the zoom lens with respect to a view angle of the lens system at each position of the focus lens and the zoom lens, the view angle being maintained constant when the focus lens moves to a position and the zoom lens moves to the target position; and a controlling device for obtaining, from the data stored in the storage device, the target position of the zoom lens when the focus lens moves based on an operation of the focus operating member, and controlling the lens driver to move the zoom lens to the obtained target position.
According to the present invention, pumping can be corrected by the lens operating unit without changing the control part of the lens unit, because a change of a view angle caused by moving the focus lens is automatically corrected by the instruction to move the zoom lens from the lens operating unit when moving the focus lens by the focus operating member of the lens operating unit.